(Pi-allyl)palladium compounds have been reported in the literature and have been found useful as chemical intermediates and catalysts. For example, such compounds have gained increasing importance as catalysts for reactions of olefins and other unsaturated organic molecules, for example in processes of oligomerization.
Although the (pi-allyl)palladium compounds have been known to be used as catalysts in the types of reactions expressed herein, there has been some difficulty in obtaining these compounds in sufficiently high quantity to make them practically available for commerical organic synthesis. This is so because (pi-allyl)palladium compounds are frequently difficult to isolate from reaction mixtures and are quite often obtained in very low yields.
In a previous patent by one of the co-inventors, Larock, U.S. Pat. No. 4,065,479, issued Dec. 27, 1977, there is disclosed a process involving vinylmercurials reacting with palladium salts and simple olefins to afford (pi-allyl)palladium compounds. This invention relates to an improvement based upon the discovery that the reaction of organomercurials, palladium salts and alkenyl- or methylenecyclopropanes and alkenyl- or methylenecyclobutanes, results in a novel ring-opening process and subsequent rearrangement which affords a valuable new regioselective route to further (pi-allyl)palladium compounds.
It is accordingly a primary objective of the present invention to provide the process and synthesis route immediately discussed above to allow the practice of a novel ring-opening process and subsequent rearrangement to prepare (pi-allyl)palladium compounds from alkenyl- or methylenecyclopropanes or alkenyl- or methylenecyclobutanes.
The method of accomplishing the above objective as well as others, including the preparation and practice of the process to yield commercially practical higher yields of product, will become apparent from the detailed description which follows hereinafter.